Hi Don, Thank you for the great explanation.
I must have had the ATT on when I did the original power measurement (rough) on the SDR I tested again and this time I get: -77dBm - Preamp On -55dBm - Preamp Off -74dBm - ATT on Just relative differences with the absolutes unique to my setup of course. The VFO signal is in the noise with the antenna disconnected from both KX2 and SDR. The VFO signal is lower when using separate antennas for each as would be expected. I was just not used to seeing a signal like that when using the SDR to track superhet's before, so it had me scratching my head for a bit until I considered the Rx architecture of the KX2(3). Thank you for helping me get everything organized in my thinking, sometimes that is a monumental task! 73 de KV4TT - Mike KX2 s/n 2300 On Fri, Dec 22, 2017 at 11:14 AM, Don Wilhelm <donw...@embarqmail.com> wrote: > Mike, > > The KX2 is fully an SDR with the "computer" in the enclosure. Yes, it has > a permanent 8kHz shift, so all the DSP operation is conducted at 8kHz (not > audio), including the nulling and suppression. > > You are hearing the actual VFO freuency - it is 8kHz from the operating > frequency of the KX2. > > If you turn on the preamp, the locally heard VFO signal level should be > reduced. The KX2 is designed to operate normally with the preamp on. > > If your KX2 and your other SDR receiver are close to each other, you could > be hearing some leakage from the KX2 circuitry rather than from the antenna > alone. > > 73, > Don W3FPR > > > On 12/22/2017 9:38 AM, Michael Zabel wrote: > >> Hello group, >> >> I received a new KX2 from Elecraft a few days ago and I am really >> enjoying >> the little GEM! >> >> As many of you already must know, the receiver performs brilliantly. I >> have >> been comparing with a couple of SDR receivers in the shack and the KX2 is >> preferred for weak signal reception in any mode. >> >> I plan to use it portable of course, but for now have it set up in the >> shack with an SDR receiver tracking with it as a panadapter. >> >> I have noticed that the KX2 produces about a -74dBm signal into the SDR >> that is connected in parallel to the same Rx antenna (through a T/R >> switch). >> >> The signal is offset about 8 kHz from the VFO , so the KX2 must use the >> offset full time where it was a menu option on the KX3 I had? >> >> For anyone using a similar setup I wonder if you see the signal at about >> the same power level? >> >> Am I correct that the nulling or supression is done at the audio stage >> within the KX2 (because I can't hear it when I tune the 2nd VFO to it in >> Dual Rx)? >> >> Thanks Elecraft for another great transceiver and thank you all on the >> group for being there as a great resource! >> >> KV4TT - Mike >> >> KX2 s/n 2300 >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to donw...@embarqmail.com >> >> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
